In a casing downhole, it is often necessary to pressurise the interior of the casing, or parts of it, during completion or operation of the well.
The interior is pressurised to expand one or more components in predetermined positions along the casing string. These components may be expandable annular barriers, rock anchors, etc.
Common for these components is that a high pressure is necessary to expand them. The high pressure may influence on other components and in severe circumstances in fact damage these components.
Therefore, these components are protected by for instance sliding elements which are adapted to be positioned in front of the components. However, since the components to be expanded require higher and higher pressure to obtain expansion, the sealing properties of the sliding elements are not sufficient to secure that the other components are not damaged.